Ecology of the burrowing amphipod, Pontoporeia affinis, in Lake Michigan / by Wayne Paul Alley.

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ment by upwelling,z fldcal:unipff. -and also ythe -dohfainant along shore
current. It must be emphasized that this junction changes with the seasons, and its location within an area is dependent on the morphometric
features of the lake and the prevailing meteorological conditions.
The profundal zone represents the most stable environment of the
lake with all areas of the profundal sharing a common low water temperature. The Pontoporeia of this region probably require three or more
years to mature, and although breeding is intermittent throughout the
year only a very small portion of the population appears to be mature at
any particular.time. The density of Pontoporeia in this zone shows a
strong inverse relationship with depth, which most likely reflects the
negative effect that depth has on the rain of suspended particulate matter.
The lack of available nutrients is probably the most restrictive element
of the profundal environment.
As Pontoporeia is the only macrobenthic invertebrate that is ubiquitously distributed throughout the sublittoral and profundal zones of the
lake, it should play an increasingly important role as an indicator of
water pollution. Cook and Powers (1964) showed that a benthic community
subjected to the effluent of the St. Joseph River contained few Pontoporeia
and an abundance of oligochaetes. On the other hand, a benthic community adjacent to Little Sable Point, which has no major tributaries, contained a large population of Pontoporeia and few oligochaetes. Ayers
and Huang (1967) included macrobenthic sampling in a pollution study of